Since frequent LOH at FHIT locus was detected in smokers of squamous cell carcinoma with p53 aberrations in Western populations (Garinis et al, 2001), we speculated that exposure of different carcinogenic agents such as HPV, cooking fume, etc. in Taiwan (Chen et al, 1990) might have caused genome instability detected by LOH of FHIT locus in lung cancer patients of different geographic regions. Here, FHIT is linked to squamous cell carcinoma.